Setting Base Idle

[slow5.0gt]

I was following the surging idle checklist while trying to set the base idle I noticed that almost no matter what the idle screw was at the base was the same about 750-400. at one point it was at 1300 for a bit after i turned it about 3 times so i started backing off now it will not stay above 600 I read in the list that this is a vacuum leak #1 cause.
Am I reading into it too much or I must tackle that vacuum leak first before trying to set the idle again

 

[BlownFiveLiter]

If you have a vacuum leak, you need to correct it before setting the base idle. The additional airflow from the leak will raise your idle speed, so setting it first will only mean you need to reset it when you fix the leak.

 

[slow5.0gt]

could a possiblity be also a bad MAF?

 

[slow5.0gt]

Ive also noticed while trying to set the idle on the car with the iac off small jumps from 600-500 rpms but with the iac plugged in the car will idle very rough before dying on its own... any help?

 

[ebk06]

You need to have the car running correct before trying to set the idle. My car just got fixed from its rough idle problem. The ECT and IAC were replaced along with some vacuum lines running under the upper intake. I think the surging idle checklist shows how to check/clean the IAC. Sounds like you need a new one though.